In case you need more #CosmologyFunFacts to break your brain, did you know that there are distant galaxies that are currently receding from us faster than the speed of light (due to cosmic expansion), and ALWAYS HAVE BEEN, and yet we have pictures of them? 🙃
https://twitter.com/astrokatie/status/1516548836709343238
I talked about this in the final lecture of my general relativity class and the students looked at me like 🤨 but I swear it’s true if you work through the math. The key is that while the GALAXIES are always receding faster than light, the LIGHT can (eventually) move toward us.
Anyway the photons from some of the distant galaxies that @NASAWebb is going to see were actually moving directly AWAY from us for about six and a half billion years before they started to move toward us, because of how the expansion rate of the universe has been changing.
Q: I thought nothing could travel faster than light?
A: Nothing can travel THROUGH SPACE faster than the speed of light but things can get farther away from us faster than the speed of light if the space between us and them gets larger very quickly, because of cosmic expansion.
A: Nothing can travel THROUGH SPACE faster than the speed of light but things can get farther away from us faster than the speed of light if the space between us and them gets larger very quickly, because of cosmic expansion.
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